Wire saw cutting is widely used in slicing semiconducting crystals, such as silicon ingot, gallium arsenide (GaAs), gallium phosphide (GaP), and the like to produce wafers for making electronic and photovoltaic devices. The wire saw slicing works through abrasive grinding action provided by an abrasive slurry consisting of a cutting fluid and abrasive particles, generally of silicon carbide (SiC), suspended in the fluid. The cutting fluid plays a critical role in achieving efficient and precise slicing by (i) suspending and carrying abrasive particles and swarf (i.e., semiconductor crystal chips produced the cutting of the crystal), (ii) lubricating the workpiece, and (iii) removing the frictional heat generated at the cutting site.
Polyalkylene glycols (PAG), in particular polyethylene glycols (PEG), are commonly used as semiconductor crystal cutting fluids. The demand for semiconductor wafers continues to grow, especially in the photovoltaic market, and with it a demand for a more cost-effective production of silicon wafers. The cost and quality of silicon wafer production can be improved by boosting cutting speed, increasing wafer yield, reducing total thickness variation (TTV) of wafers, reducing saw marks and warp, decreasing wafer thickness, and prolonging the lifetime of cutting wires. All these improvements require higher performance cutting fluids that can more effectively disperse the abrasive, e.g., SiC particles, and crystal, e.g., silicon, swarf particles.
One known solution is to add a dispersant, such as polyelectrolyte, to the PAG to produce formulated PAG-based cutting fluids. However, this additional formulation step increases the complexity and cost of the cutting fluid production. The invention is to produce PAG materials as cutting fluids with improved dispersing ability for SiC and Si particles but does not need the additional step of adding dispersants.